Vehicle anti-theft system including vehicle identification numbers programmed into on-board computers

ABSTRACT

A vehicle anti-theft system includes programming vehicle identification numbers or a corresponding identifier value into a read-only memory portion of each computer on board the vehicle. The computers are all linked through a multiplex communication system that has a monitoring port. The monitoring port facilitates coupling an external device to the multiplex communication link. The external monitoring device is used to determine the contents of the read only memory portion on each component to determine whether any of the components were stolen from another vehicle, for example.

BACKGROUND OF THE INVENTION

This invention generally relates to an anti-theft system for vehicles.More particularly, this invention relates to a system for inhibiting orpreventing the theft of vehicle components by including a unique vehicleidentifier on each component.

Vehicle theft is a substantial, widespread problem. Most often, when avehicle is stolen it is dismantled into component parts, which are soldindividually. An additional problem is that certain vehicle components,such as air-bags and stereos, are stolen from vehicles and later sold.

One attempt to reduce the ability to sell stolen vehicles and componentparts has been to physically or mechanically etch a vehicleidentification number onto certain portions of a vehicle. This approachhas several shortcomings and drawbacks. First, physically etching in anidentification number to a plurality of component parts typically provesprohibitively expensive. Further, physical etching is relatively easyfor a thief to detect and, in many circumstances, alter. Moreover, thereis no efficient way to verify that a particular component on a vehiclehas a legitimate identification number without visually inspecting it,which may require removing that part from the vehicle. This makes thetask of monitoring stolen parts prohibitively expensive.

This invention overcomes many of the short-fallings and drawbacks of theprior art. This invention provides an efficient method and system foridentifying component parts of a vehicle. Moreover, a system designedaccording to this invention provides for easy monitoring for detectingstolen parts. Further, this invention includes a strategy forprohibiting a thief from altering an identification given to a componentpart, which discourages theft because it reduces the ability to sell astolen part.

SUMMARY OF THE INVENTION

In general terms this invention is a vehicle security system forpreventing or deterring the theft of vehicles and component parts thatincludes placing a vehicle identifier into a memory portion of eachcomputer on board the vehicle. The system includes a multiplexcommunication link. A plurality of vehicle components each have acomputer. The computers are coupled to the multiplex communication link.Each computer has a memory portion that includes a vehicle identifierthat corresponds to a vehicle identification number of the vehicle. Themultiplex communication link includes a monitoring port that isaccessible from outside the vehicle. An interface device is connected tothe monitoring port and used to access the computers that are connectedto the communication link so that the vehicle identifier on eachcomponent part can be read.

The method of this invention includes three basic steps. First, avehicle identification number is assigned to the vehicle. Second, avehicle identifier that corresponds to the vehicle identification numberis generated. Lastly, the vehicle identifier is stored in a read-onlymemory portion of each component part that includes a computer. Thecomputer memories can later be accessed to determine whether a componentpart is on an appropriate vehicle.

The various features and advantages of this invention will becomeapparent to those skilled in the art from the following detaileddescription of the presently preferred embodiment. The drawings thataccompany the detailed description can be described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an anti-theft system designedaccording to this invention.

FIG. 2 is a schematic illustration of a read only memory portion of acomponent part computer designed according to this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 schematically illustrates a vehicle 20 that includes ananti-theft system 22. A plurality of vehicle component parts 24 through34 either comprise a computer or include a computer. Each of thecomponent part computers includes a read only memory portion 40 that isprogrammed to include a vehicle identification number associated withthe vehicle 20 or an identifier corresponding to the vehicleidentification number.

The computer of each component part is coupled to a multiplex bus line42, which can be any conventional multiplex communication link. Examplesof suitable multiplexed communication links include the known SAE J-1850protocol and the CAN protocol. A vehicle monitoring port 44 is alsocoupled to the multiplex communication link 42. An external monitoringdevice 46 is used to communicate through the vehicle monitoring port 44to access the multiplex communication link 42. The external monitoringdevice 46 preferably includes a visual display for indicatinginformation that is obtained from the various component parts of thevehicle and further preferably includes a data base that facilitatesdetermining whether an identifier programmed into each component partcomputer memory is valid or appropriate.

The coupling 48 between the monitoring device 46 and the monitoring port44, schematically illustrated in FIG. 1, can be any conventional hardwiring arrangement or a radio frequency communication arrangement, forexample. The external monitoring device facilitates quickly andefficiently determining whether any of the component parts that areconnected to the multiplex communication link 42 were inappropriatelyinstalled on the vehicle 20.

The read only memory portion 40 preferably is a one-time programmableread only memory. In the presently preferred embodiment, the memoryportion 40 includes metal fuses that are blown with a high voltage. Thememory portion 40 is only programmable so long as the correspondingmetal fuse or fuses is not blown. Accordingly, once the memory portion40 is appropriately programmed, the appropriate fuse or fuses is blownto prevent alteration of or tampering with the contents of the memoryportion 40. Accordingly, the memory portion 40 is a non-volatile,tamper-resistant memory that stores an identifier corresponding to avehicle identification number, which is either impossible or verydifficult to alter.

In the presently preferred embodiment, all component parts aremanufactured with a blank or empty memory portion 40. The vehicleidentification number value preferably is programmed into the componentparts at the end of an assembly line. This can be accomplished becauseeach of the computers are connected to the multiplex communication link42 and, therefore, can be accessed through the vehicle monitoring port44. Programming in the vehicle identification number values at the endof the vehicle assembly process provides the advantage of eliminating aneed for coordinating parts to vehicles during assembly procedures.

Legitimately manufactured replacement component parts preferablyinitially have a blank memory portion 40. This memory portion can remainblank or be programmed with a vehicle identification number after thatcomponent part is installed on a vehicle.

A system designed according to this invention has many advantages andpotential uses. For example, an insurance company representative coulduse an external monitoring device 46 to test and determine whetherreplacement parts used at a repair shop are authentic, dealer-approvedcomponent parts. Similarly, a vehicle identification number value database provides the ability to determine whether replacement parts thatwere used were stolen from another vehicle. Those skilled in the artwill realize other advantages and applications for a system designedaccording to this invention.

Although vehicle identification numbers provide an exact way to match upa component part with an appropriate vehicle, in many circumstances itis useful to program a separate vehicle identifier into the memoryportions 40. Current vehicle identification number format includesseventeen alphanumeric characters. This provides 1.7×10²⁴ possiblecombinations. 81 bits of computer memory are required where a full 17character identification number is implemented. Providing that muchmemory in the memory portion 40 may prove prohibitively expensive incertain circumstances. Accordingly, this invention includes a method ofencoding a vehicle identification number that salves memory and,therefore, reduces the costs associated with a system for implementingthis invention.

FIG. 2 schematically illustrates a preferred example of the read onlymemory portion 40. The memory portion 40 is divided into three sections,a first section 50, a second section 52 and a third section 53. In thepreferred embodiment, the first section 50 includes 26 bits. A vehicleidentifier preferably is stored in the first section 50. The vehicleidentifier is generated using a cyclic redundancy code or otherconventional hash function value. The vehicle identifier has a directcorrespondence to the vehicle identification number assigned to thevehicle at the time of manufacture. Providing a twenty-six bitidentifier that corresponds to a vehicle identification number appearsto be sufficient to avoid having more than one vehicle identificationnumber correspond to the same vehicle identifier. Having twenty-six bitsavailable for the vehicle identifier, assuming that the cyclicredundancy code function provides a uniform hash distribution of vehicleidentification numbers, results in a one in 67 million chance of avehicle identifier corresponding to an inappropriate vehicleidentification number. Embodiments where greater odds of an accidentalmatch are required may include more than twenty-six bits of memory inthe first memory section 50.

The memory portion 40 is made tamper-proof by utilizing read onlymemory. As mentioned above, one-time programmable read only memory ispreferred. One time programmable read only memory initially begins withall bits set at one polarity (typically either positive or negative). Asthe vehicle identifier is programmed into the first memory section 50,the polarity of certain bits is altered. In one example, the firstmemory section 50 includes all bits having a 1 (positive) value. As thevehicle identifier is programmed into the first section 50, certain ofthe bits are blown or changed to a 0 (negative) value. The number ofbits with a changed polarity is programmed into the second memorysection 52 after the first section has been programmed.

The second memory section 52 preferably includes five bits that areutilized to indicate the number of bits in the first section 50 having achosen polarity after the vehicle identifier has been programmed. Thecombination of the first section 50 and the second section 52 providesan indicator of tampering of the memory portion 40. The vehicleidentifier in the first section 50 can only be altered by changing thepolarity of one or more bits within the first section 50. This wouldincrease the number of bits having a changed polarity, which would nolonger match the number indicated in the second section 52.

The second section 52 preferably begins with the five bits having anopposite polarity from the initial polarity of the bits within the firstsection 50 to provide enhanced tamper-resistant characteristics. Underthese circumstances, if someone altered the contents of the firstsection 50 without altering the contents of the second section 52,tampering would be evident. Further, if one attempted to alter thecontents of both sections, tampering is still evident. Blowingadditional bits in the first section 50 would result in more negativepolarity bits, for example. While blowing additional bits in the secondsection 52 would result in less negative polarity bits. Accordingly, anyalteration of the first section 50 or the second section 52 indicatesthat the contents of the memory portion have been tampered.

In the illustrated embodiment, the memory portion 40 includes a thirdsection 53. The third section 53 preferably includes one bit that isleft unaltered on original equipment and blown for replacementequipment. This third section, therefore, provides a convenient way ofindicating originally installed equipment or authorized replacementparts.

In another example, the memory portion 40 includes the vehicleidentifier and a fuse that is blown to inhibit further writing to theread only memory portion. Since this capability may not be available onmicrocontrollers that are included in many vehicle component parts, thecyclic redundancy code approach that is described above likely has morewidespread usefulness.

Another example includes having a single original-replacement bit thatinitially has a 1 (positive) value. When a component part is installedas original equipment, the single bit is blown or given a 0 (negative)value. Therefore, the single bit represents a proof of purchase forlegitimate replacement parts that would be absent from any componentpart taken from a stolen or junked vehicle. The latter embodiment ismost useful to insurance companies that desire to deter the theft ofcomponent parts and would only accept new component parts duringauthorized vehicle repair, for example.

Coupling all of the memory portions 40 to the communication link 42 andproviding the vehicle monitoring port 44 provides authorized individualsor agencies with the ability to quickly, efficiently and accuratelydetermine whether any component parts on a particular vehicle are stolenor were inappropriately installed depending on the circumstances.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed embodiment may becomeapparent to those skilled in the art that do not necessarily depart fromthe purview and spirit of this invention. Accordingly, the followingclaims must be studied to determine the scope of legal protectionafforded this invention.

What is claimed is:
 1. A vehicle security system, comprising:a multiplexcommunication link; a plurality of components, each having a computercoupled to said multiplex communication link, each said computer havinga memory portion that includes a vehicle identifier that corresponds toa vehicle identification number of the vehicle, each said vehicleidentifier being identical; and a monitoring port, accessible fromoutside the vehicle and coupled to said multiplex communication link. 2.The system of claim 1, further comprising an interface device adapted tobe coupled to said monitoring port and having a memory reading portionso that each said vehicle identifier can be read from each said computermemory portion.
 3. The system of claim 1, wherein each said computermemory portion comprises a one time programmable read only memory havinga blocking element that blocks manipulation or destruction of saidvehicle identifier once said identifier is programmed into said memory.4. The system of claim 3, wherein said blocking element comprises a fusethat is adapted to be blown after said vehicle identifier is programmedinto said memory portion.
 5. The system of claim 1, wherein each saidmemory portion comprises a first and second module, said first moduleseach including a plurality of bits that each have a first or secondpolarity, said first module containing said vehicle identifier wherein anumber of bits having said first polarity corresponds to saididentifier, said second module containing information corresponding tosaid number of bits having said first polarity.
 6. The system of claim5, wherein each said memory portion further comprises a third moduleincluding an installation identifier that identifies whether saidcomponent was installed by a vehicle manufacturer or by some othersource.
 7. The system of claim 5, wherein each said second moduleincludes a plurality of bits each having said first or second polarity,a number of said second module bits having said first polaritycorresponds to said number of first module bits having said firstpolarity and wherein said first and second modules are interrelated suchthat an increase in said number of first module bits having said firstpolarity is consistent with a decrease in said number of second modulebits having said first polarity.
 8. A vehicle security system,comprising:a multiplex communication link; a plurality of components,each having a computer coupled to said communication link, each saidcomputer having a memory portion that includes a source identifier thatcorresponds to a source of each said component and indicates whethereach said component source is an original equipment manufacturer; and amonitoring port, accessible from outside the vehicle and coupled to saidcommunication link.
 9. The system of claim 8, further comprising aninterface device adapted to be coupled to said monitoring port andhaving a memory reading portion so that each said source identifier canbe read from each said computer memory portion.
 10. The system of claim8, wherein each said computer memory portion further includes a vehicleidentifier that corresponds to a vehicle identification numberassociated with the vehicle.
 11. A method of deterring theft of vehiclecomponent parts wherein the component parts each include a computer,comprising the steps of:(A) assigning a vehicle identification number tothe vehicle; (B) generating a vehicle identifier corresponding to thevehicle identification number; and (C) storing the vehicle identifier ina memory portion of the computer included with each component part. 12.The method of claim 11, further comprising the step of comparing thevehicle identifier in the memory portion of each component part computerwith the vehicle identifier from step (B) to determine whether any ofthe component parts have been removed or replaced after step (C) wasperformed.
 13. The method of claim 11, further comprising linking allthe computers included in the component parts with a multiplexcommunication system, accessing the vehicle identifiers stored on thelinked computers, and comparing an existing vehicle identifier on eachcomputer with the vehicle identifier from step (B).
 14. The method ofclaim 13, wherein the vehicle identifiers are accessed by coupling amonitoring device that is separate from the vehicle to the communicationsystem and reading the contents of the memory portion of each computer,using the monitoring device.
 15. The method of claim 11, wherein step(C) is performed by instigating a blocking element in the memory portionof each computer after the vehicle identifier is stored, wherein theblocking element prevents further alteration of the contents of thememory portion.
 16. The method of claim 15, wherein step (C) isperformed by blowing a fuse that is associated with the memory portionof each computer after the vehicle identifier is stored, wherein thememory portion cannot be altered after the fuse has been blown.
 17. Themethod of claim 11, wherein step (B) is performed by selecting portionsof the vehicle identification number from step (A) in a preselectedorder.
 18. The method of claim 11, wherein step (C) is performed byplacing the vehicle identifier in a first section of the memory portionof each computer including a plurality of bits having a first or secondpolarity, determining a number of bits within the first section havingthe first polarity, and programming a second section of the memoryportion such that it contains an indicator of the number of firstsection bits having the first polarity.
 19. The method of claim 18,further comprising programming a third section of the memory portion toinclude an indicator of a source of the component part.
 20. A vehiclesecurity system, comprising:a multiplex communication link; a pluralityof components, each having a computer coupled to said multiplexcommunication link, each said computer having a memory portion thatincludes a vehicle identifier that corresponds to a vehicleidentification number of the vehicle; each said computer memory portioncomprising a one time programmable read only memory having a blockingelement that blocks manipulation or destruction of said vehicleidentifier once said identifier is programmed into said memory, saidblocking element comprising a fuse that is adapted to be blown aftersaid vehicle identifier is programmed into said memory portion; and amonitoring port, accessible from outside the vehicle and coupled to saidmultiplex communication link.
 21. A vehicle security system,comprising:a multiplex communication link; a plurality of components,each having a computer coupled to said multiplex communication link,each said computer having a memory portion that includes a vehicleidentifier that corresponds to a vehicle identification number of thevehicle; each said memory portion including a first, second and thirdmodule, said first modules each including a plurality of bits that eachhave a first or second polarity, said first module containing saidvehicle identifier wherein a number of bits having said first polaritycorresponds to said identifier, said second module containinginformation corresponding to said number of bits having said firstpolarity, said third module including an installation identifier thatidentifies whether said component was installed by a vehiclemanufacturer or by some other source; each said second module includinga plurality of bits each having said first or second polarity, a numberof said second module bits having said first polarity corresponding tosaid number of first module bits having said first polarity and whereinsaid first and second modules are interrelated such that an increase insaid number of first module bits having said first polarity isconsistent with a decrease in said number of second module bits havingsaid polarity.